Characterization and Selection of Polymer Materials for Binary Munitions Storage. Part 3. Branch Content Determination

摘要

Previous studies of potential failure mechanisms in polyolefin containers for binary munitions have established that good environmental stress cracking resistance (ESCR) is an essential property of a successful candidate resin. In this regard, it was also found that the linear low density polyethylenes (LLDPE's) offered performance advantages, and that the key resin characteristic influencing ESCR is the extent of short chain branching. A characterization method which involves using precision lattice parameter determination for correlation with the branch content has been implemented. The data acquisition method obtains the required wide angle X ray scattering (WAXS) data at greatly enhanced speed, without sacrificing any accuracy. The data acquisition system combines a position-sensitive X ray detector with a 65 kilobyte microcomputer capable of operating as multichannel analyzer and of performing immediate data analysis. The method is applied to the determination of branch content in a series of polyethylene resins for binary munitions storage. In addition, the resins are characterized and compared in terms of crystallinity and molecular weight distribution.